The present invention relates to electric discharge lamps having an ionizable gas discharge path with a luminescent material coating the walls of the discharge path, and more particularly, to a plurality of fluorescent electric discharge lamp elements supported on a base containing an integral self-contained electronic ballasting means, comprising a replaceable 3-way compact fluorescent lamp.
Because of the demand for increased energy conservation due to the increased replacement and operating costs, researchers and innovators have been attempting to develop compact electric discharge lamps, such a fluorescent lamps, as screw-in replacements for the standard incandescent bulb. Up to now, these attempts have been hampered by lagging technologies that made large bulky inefficient assemblies that were expensive to manufacture and quite cumbersome at best.
Electromagnetic ballasts, ones which were the predecessors to the electronic ballasts, had the disadvantage of being heavy because of the metal core, failed when overheated because of insufficient cooling and heat-sinking, and were excessively large when compared to a compact bulb itself.
If one were to consider the development of a 3-way triple biaxial fluorescent lamp using electromagnetic ballasts, a rather unwieldy assembly would evolve. It could become necessary to have three electromagnetic ballasts, each correctly sized for each of the three biaxial lamp elements.
Three-way incandescent bulbs are capable of supplying three levels of illumination by controlling the switching sequence that applies power to the two filaments. The common connection between the two filaments connects to the shell of a 3-contact medium or mogul base. The low power filament connects to the ring contact, which lies intermediate the central contact and the shell; and the medium power filament connects to the center contact of the base.
As a replacement for a standard 3-way incandescent bulb having a 3-contact medium base, the switching for the incandescent filaments is sequenced such that the first switch position is the xe2x80x9coffxe2x80x9d position. The second switch position, xe2x80x9clow,xe2x80x9d connects the first lamp filament to the applied power line; the third switch position, xe2x80x9cmedium,xe2x80x9d connects the second lamp filament to the applied power line; and the fourth switch position, xe2x80x9chigh,xe2x80x9d connects both the first and second lamp filaments together in parallel, to the applied power line.
U.S. Pat. No. 5,831,395, granted Nov. 3, 1998, to G. W. Mortimer, et al., discloses an adapter having a control circuit and ballasting means that controls the light output of a gas discharge lamp in response to switches that are external to the ballast. Three levels of light output with single or multiple lamps are provided. In one embodiment, it can be mounted in a standard three-way socket for incandescent lamps.
In the event the lamp voltage requirement is too high, Mortimer further teaches that a voltage doubling rectifier circuit for the electronic ballast is needed for optimal operating efficiency. The present invention obviates the need for a voltage doubling rectifier circuit by providing an improved fluorescent lamp starting means.
U.S. Pat. No. 5,612,597, granted Mar. 18, 1997, to P. Wood, discloses an oscillating driver circuit with power factor correction and an electronic lamp ballast employing the same and driver method.
Wood further teaches of a basic prior art electronic ballast that consists of L-C series resonant circuits with the lamps connected across one of the reactances. He also teaches that because fluorescent lamps do not require high striking voltages, a Q of two or three is sufficient to produce a xe2x80x9cflatxe2x80x9d Q curve.
In the present in invention, a novel high voltage starting circuit that optimizes the serially connected L-C circuit for optimum transient response, as opposed to the prior art L-C series resonant response is used.
U.S. Pat. No. 5,424,610, granted Jun. 13, 1995, to B. A. Pelton, discloses an outboard ballast that allows a compact fluorescent light bulb and its associated ballast to be positioned within a standard table lamp having a standard-size harp.
Pelton teaches of a table lamp configuration using a compact fluorescent lamp (without having an internal ballast), screwed into a lamp socket, which supports a lamp harp, to which an external ballast is mounted. The present invention relates to a compact 3-way fluorescent lamp, having a self-contained ballasting means, to be used as a replacement for a 3-way incandescent bulb.
U.S. Pat. No. 5,309,062, granted May 3, 1994, to R. A. Perkins, discloses a compact low-pressure gas discharge lamp assembly having a base and a plurality of low-pressure gas discharge light generating elements that is capable of being individually energized. An external ballast circuit assembly is provided to supply electrical energy to a variable number of low-pressure gas discharge elements. The output of the ballast connects to a three position switch, where in the first position connects to a single element; in the second position, to two elements connected in parallel; and in the third position, to all three elements. The operating frequency of the ballast varies as a function of the number of light-generating elements connected by the switch to the ballast circuit.
Perkins teaches of a compact fluorescent lamp arrangement, having an externally located electronic ballast, electrically sized to the maximum combined wattage of the three lamp elements combined. In the xe2x80x9cmediumxe2x80x9d connection, two lamp elements are operated in parallel. The present invention uses three biaxially arranged tubes, symmetrically arranged and mounted on a single base, each tube spaced 120 degrees apart, where two of the tubes are joined and bonded to form a single double biaxial tube, which comprises two tube elements essentially connected serially.
U.S. Pat. No. 4,958,102, granted Sep. 18, 1990, to W. E. Wilson, et al., discloses a three-way lamp having two orthogonally mounted, U-shaped gas discharge light tubes, one larger than the other, mounted in the same housing; having three terminals arranged in the same configuration as a three-way incandescent lamp.
Wilson, et al., teaches of a three-way gas discharge lamp, having magnetic ballasts, as opposed to having electronic ballasts integrated into the housing structure. A lamp of this type could have been manufactured only by extremely complex manufacturing processes.
U.S. Pat. No. 4,853,591, granted Aug. 1, 1989, to L. Klein, et al., discloses a gas discharge vessel comprising at least two U-shaped units having two longitudinal leg portions extending parallel to each other and a cross element or base portion of the U, connecting the leg portions to the base of the U. To facilitate lamp starting, an auxiliary electrode is pinch sealed adjacent the cross connection and coupled by an impedance to the xe2x80x9chotxe2x80x9d current carrying electrode.
In the present invention, the need for an auxiliary electrode as required by Klein, is obviated by the introduction of a novel high voltage starting circuit that optimizes the serially connected L-C circuit for optimum transient response as opposed to the prior art optimization of the L-C series resonant response.
U.S. Pat. No. 4,748,368, granted May 31, 1988, to W. E. Wilson, et al., discloses a three-way lamp having two orthogonally mounted, U-shaped gas discharge light tubes, one larger than the other, mounted in the same light-transmitting bulb; having three terminals arranged in the same configuration as a three-way incandescent lamp.
Wilson, et al., further teaches of a gas discharge lamp for use as a replacement for an incandescent bulb, where two U-shaped gas discharge tubes, one larger than the other, are mounted orthogonally on the same housing. It is further taught the use of magnetic ballasts, which when operated at 60 Hertz, become unduly large and operate at substantially higher than ambient temperatures. The present invention uses three biaxially arranged tubes, symmetrically arranged and mounted on a single base, each tube spaced 120 degrees apart, where two of the tubes are joined and bonded to form a single double biaxial tube.
U.S. Pat. No. 3,899,712, granted Aug. 12, 1975, to H. L. Whitting, discloses an improved electric discharge lamp comprising a tapered cylinder envelope having a helical shaped channel of nonuniform pitch for providing a circumferential discharge path around the envelope with a pair of electrodes disposed adjacent each end of the discharge path. The standard screw-in base supports a ballast device located within the central region of the lamp.
Whitting teaches of single-way helical gas discharge lamp using magnetic ballasts, whereas the present invention relates to a 3-way design using electronic ballasts.
Other prior art includes U.S. Pat. No. 5,233,370, granted Aug. 3, 1993, to O. E. Nilssen, and U.S. Pat. No. 5,128,590, granted Jul. 7, 1992, to W. Holzer, discloses compact fluorescent lamps that are screw-in types and are self ballasting. However, neither teaches of being designed for use as 3-way replacement lamps.
What is needed is a compact 3-way fluorescent lamp that is directly interchangeable with a 3-way incandescent bulb to serve as an alternative replacement that is easy to manufacture and is lower in cost. This lamp should be of one-piece construction, having dual elements, and include a dual integrated electronic ballasting arrangement. It should also provide the equivalent illumination as its predecessor. In this regard, the present invention fulfills this need.
The present invention relates to a compact 3-way fluorescent lamp that is designed to serve as a replacement for a 3-way incandescent bulb. Even though the initial cost of a fluorescent lamp is greater than an incandescent bulb, a 3-way fluorescent lamp is advantageous for use because an 11/22/33 watt fluorescent lamp produces the same illumination equivalent to a 50/100/150 incandescent bulb and is more efficient to operate. In addition, there is less maintenance since it does not have to be replaced as frequently as the incandescent bulb because of its enhanced longevity.
The newly designed 3-way fluorescent lamp uses the same base configuration and the same electrical connections as a standard 50/100/150 watt incandescent bulb. The base is a standard 3-contact medium base, where the outer shell connects to the neutral wire to minimize a shock hazard should the user inadvertently come in contact with the shell when installing the lamp into its socket. The ring contact connects to the low wattage unit and the center contact, to the medium wattage unit.
In the preferred embodiment, an ideal lamp configuration for use as a 3-way compact fluorescent lamp is one where there appears to have three individual U-shaped lamp elements, where each lamp element is equally spaced 120 degrees apart circumferentially. Ideally, each lamp element comprises a U-shaped tube that is secured to a circular lamp housing.
Each U-shaped tube has two longitudinal leg portions that extend downwards and are parallel to each other.
The low wattage lamp element has a lamp filament-carrying electrode at each end of the U-shaped tube, where the ends are glass welded and sealed.
The medium wattage lamp, however, is comprised of two U-shaped tube elements that are bridged together using a cross element at the base of the U-shaped tubes. A lamp filament-carrying electrode is installed at the extreme ends of the U-shaped tubes, where each end is ultimately glass welded and sealed. The U-shaped ends on either side of the cross element are also glass welded and sealed. A continuous gas discharge path now exists between the two filaments traversing through a first U-shaped tube, a cross element, and a second U-shaped tube.
This configuration is quite advantageous and desirable because the light output is enhanced over having only one U-shaped structure. The two bridged, U-shaped structures perform essentially as two 11-watt lamps that are serially connected. In this configuration, when the optimum mercury vapor pressure is achieved, a total wattage of 22-watts, results.
In addition, the configuration of having the three U-shaped elements equally spaced 120 degrees apart, creates the uniform symmetry that is observed in a typical triple biaxial compact fluorescent lamp.
The primary advantage of using a conventional single U-shaped tube in combination with a pair of bridged U-shaped tubes is that only two lower wattage electronic ballast circuits are neededxe2x80x94a 11-watt ballast for the single U-shaped unit and a 22-watt ballast for the bridged dual U-shaped unit.
In another aspect of the present invention, the ballast circuit is improved so that a higher lamp ignition voltage is attained. This is accomplished by optimizing the L-C circuit parameters for optimum transient performance, instead of optimizing for the optimum resonant frequency response.
With the higher starting voltage, need for an auxiliary igniting electrode is obviated, resulting in a reduced manufacturing cost.
To reduce the amount of electromagnetic radiation, emanated by the high frequency switching transients of the MOSFETs, a 3-element pi-section EMI low-pass filter is used to reduce the amount of conducted and radiated interference.
To further eliminate the possibility of creating a fire hazard, a fusible link (fusister) is provided to disconnect the ballast circuitry in the event of a catastrophic failure, such as a short circuit.
Accordingly, it is therefore an object of the present invention to provide a novel compact 3-way fluorescent lamp that can be used as a replacement for an incandescent 3-way lamp.
It is another object of the present invention to provide a novel compact 3-way fluorescent lamp that uses only two fluorescent tubes, where one tube has twice the wattage rating of the smaller rated tube.
It is still another object of the present invention to provide a novel compact 3-way fluorescent lamp, comprised of 3 U-shaped tubes, where the lower wattage unit is a single U-shaped tube and the higher wattage unit is comprised of a pair of U-shaped tubes, having a cross connection at the base of the tubes, giving a continuous gas discharge path through a first U-shaped tube, a cross connecting element, and a second U-shaped tube.
It is still yet another object of the present invention to provide a novel compact 3-way fluorescent lamp that has the three U-shaped tubes spaced equally 120 degrees apart upon the top of the ballast housing.
It is a further object of the present invention to provide a novel compact 3-way fluorescent lamp that uses a dual ballasting arrangement for starting and operating the two fluorescent lamp unitsxe2x80x94comprising a low wattage ballast circuit and a medium wattage circuit.
It is still a further object of the present invention to provide a novel compact 3-way fluorescent lamp that uses an integrated pair of electronic ballasts having an improved lamp igniting circuit, one that optimizes the transient voltage performance to eliminate the need for an auxiliary igniting electrode in the dual U-shaped lamp.
It is still yet a further object of the present invention to provide a novel compact 3-way fluorescent lamp that utilizes an EMI filter to reduce the electromagnetic interference caused by the switching of the MOSFETs.
A final object of the present invention is to provide a novel compact 3-way fluorescent lamp that utilizes a fusible link (fusister) to disconnect the ballast circuitry in the event of a catastrophic failure, such as a short circuit.
These and other objects of the present invention will become apparent upon further review and understanding of the detailed specification and drawings that follow.